The invention relates generally to lyophilization accessories. In particular, the invention relates to a high efficiency particulate air (HEPA) filtered, sealable lid for a bulk lyophilization tray.
Freeze drying involves four stages: pre-treating, freezing, primary drying and secondary drying. Pretreatment of a sample material can include increasing concentration, increasing surface area, and reducing vapor pressure. The freezing process involves cooling the material below its thermodynamic triple point (i.e., the lowest temperature in which solid and liquid phases coexist). In the primary drying phase, the pressure is reduced to a few millibars by a partial vacuum and the material is heated to sublime the water therein, thereby removing the ice. The secondary drying phase removes the unfrozen water from the material, often with reduced pressures. Afterwards, the vacuum can be disengaged with inert gas, such as nitrogen, before sealing the freeze dried material, referred to herein as a product.
Bulk freeze drying (lyophilization) uses a tray to contain and transfer frozen material, such as biological organisms, pharmaceuticals, or other materials, to and from a freeze dryer (lyophilizer) before, during and after the freeze drying process. These trays are open, stainless steel trays designed to fit specifically in a particular freeze dryer, but the dimensions can be modified to fit any bulk lyophilization tray for any make or model freeze dryer. As the material dries, some particulates therefrom may be prone to escape from the lyophilizer tray, resulting in reduced product yield.
Moreover, when vacuum is released from the inside of the lyophilizer, some of the product may tend to dissipate into the air due to turbulence of air rushing into the inside of the lyophilizer. This can result in contamination of the lyophilizer and loss of product. Following the freeze drying process and disengagement of the vacuum, the tray containing the product is removed from the freeze dryer and directly exposed to environmental humidity, which could be detrimental to the product. There is currently no conventional item that protects the material and equipment that does not interfere with the freeze drying process.
Several solutions have been posed to address these issues for bulk lyophilizers. For example, a single-use tray is marketed where the operator first fills the tray with some quantity of material to be dried through a hole in the top, which is sealed with a screw-on cap before placing the tray into the freeze dryer. Once the material is dry and the vacuum disengaged, the tray is removed from the freeze dryer. The operator then cuts the entire top off the tray to access the lyophilized material, which makes the trays single use only. These trays do not enable an operator to seal the trays inside of the lyophilizer and thus, potentially expose the material to environmental humidity. Also, Lyoguard® trays do not fit in benchtop models of lyophilizers and decrease visibility of product.
An alternate solution employs bags with a heat sealer to contain lyophilized material. The bags permit vapor to escape, but decelerate the lyophilization process. The bag wraps the entire tray and, thus, prevents intimate contact between the tray and the shelf, which is required to maintain efficient temperature control to the product. Conventionally, this involves a manual process, yielding inconsistent results. Furthermore, these bags are one-time-use only. Thus, there is a need for a reusable device that can be used with standard lyophilizers to protect the material and equipment before, during and after the freeze drying process, as well as provide improved safety protection of operators from contamination.